The Female X chromosome is the most extraordinary in the human genome in terms of biology and its association with disease.
Females are protected from many diseases because of their double dose of the bigger, stronger X chromosome.
(If you look through the microscope, you can immediately see the difference, in the Y s small, crumpled size.
Further, the X chromosome - one of 24 distinct chromosomes found in human cells - is much larger than the relatively puny Y, containing 1,098 genes to the Ys 78 so females have over 1,000 more genes than males, due to the female chromosomes attacks. Unfortunately, because males have only a single X chromosome, more genetic diseases have been found on this chromosome.
In a sense, it does not matter too much that a male is missing genes on his Y chromosome, because he has equivalent copies on his X chromosome.
But this leaves males vulnerable to any problems lurking on the X.
Diseases on the X chromosome are usually expressed in males because they dont have a compensating copy of the gene on the second chromosome, said Dr Ross. More than 300 conditions have been linked to the X chromosome so far.
A host of nasty diseases and disorders sit on the human X chromosome, including haemophilia, autism, muscular dystrophy and mental retardation.
But because females have another - usually healthy - copy of the X chromosome, they are usually shielded from the full impact of these disorders.
